// Copyright (c) Jupyter Development Team.
// Distributed under the terms of the Modified BSD License.

import { expect } from 'chai';

import { ClientSession } from '@jupyterlab/apputils';

import { each } from '@phosphor/algorithm';

import { CodeCell, MarkdownCell, RawCell } from '@jupyterlab/cells';

import { NotebookModel } from '@jupyterlab/notebook';

import { NotebookActions } from '@jupyterlab/notebook';

import { Notebook } from '@jupyterlab/notebook';

import {
  acceptDialog,
  createClientSession,
  dismissDialog,
  sleep,
  NBTestUtils
} from '@jupyterlab/testutils';

const ERROR_INPUT = 'a = foo';

const JUPYTER_CELL_MIME = 'application/vnd.jupyter.cells';

describe('@jupyterlab/notebook', () => {
  const rendermime = NBTestUtils.defaultRenderMime();

  describe('NotebookActions', () => {
    let widget: Notebook;
    let session: ClientSession;
    let ipySession: ClientSession;

    before(async () => {
      session = await createClientSession();
      ipySession = await createClientSession({
        kernelPreference: { name: 'ipython' }
      });
      await Promise.all([ipySession.initialize(), session.initialize()]);
    });

    beforeEach(() => {
      widget = new Notebook({
        rendermime,
        contentFactory: NBTestUtils.createNotebookFactory(),
        mimeTypeService: NBTestUtils.mimeTypeService
      });
      const model = new NotebookModel();
      model.fromJSON(NBTestUtils.DEFAULT_CONTENT);
      widget.model = model;

      widget.activeCellIndex = 0;
    });

    afterEach(() => {
      widget.dispose();
      NBTestUtils.clipboard.clear();
    });

    after(() => {
      return Promise.all([session.shutdown(), ipySession.shutdown()]);
    });

    describe('#executed', () => {
      it('should emit when Markdown and code cells are run', async () => {
        const cell = widget.activeCell as CodeCell;
        const next = widget.widgets[1] as MarkdownCell;
        let emitted = 0;

        widget.select(next);
        cell.model.outputs.clear();
        next.rendered = false;
        NotebookActions.executed.connect(() => {
          emitted += 1;
        });

        await NotebookActions.run(widget, session);
        expect(emitted).to.equal(2);
        expect(next.rendered).to.equal(true);
      });
    });

    describe('#splitCell({})', () => {
      it('should split the active cell into two cells', () => {
        const cell = widget.activeCell;
        const source = 'thisisasamplestringwithnospaces';
        cell.model.value.text = source;
        const index = widget.activeCellIndex;
        const editor = cell.editor;
        editor.setCursorPosition(editor.getPositionAt(10));
        NotebookActions.splitCell(widget);
        const cells = widget.model.cells;
        const newSource =
          cells.get(index).value.text + cells.get(index + 1).value.text;
        expect(newSource).to.equal(source);
      });

      it('should preserve leading white space in the second cell', () => {
        const cell = widget.activeCell;
        const source = 'this\n\n   is a test';
        cell.model.value.text = source;
        const editor = cell.editor;
        editor.setCursorPosition(editor.getPositionAt(4));
        NotebookActions.splitCell(widget);
        expect(widget.activeCell.model.value.text).to.equal('   is a test');
      });

      it('should clear the existing selection', () => {
        each(widget.widgets, child => {
          widget.select(child);
        });
        NotebookActions.splitCell(widget);
        for (let i = 0; i < widget.widgets.length; i++) {
          if (i === widget.activeCellIndex) {
            continue;
          }
          expect(widget.isSelected(widget.widgets[i])).to.equal(false);
        }
      });

      it('should activate the second cell', () => {
        NotebookActions.splitCell(widget);
        expect(widget.activeCellIndex).to.equal(1);
      });

      it('should preserve the types of each cell', () => {
        NotebookActions.changeCellType(widget, 'markdown');
        NotebookActions.splitCell(widget);
        expect(widget.activeCell).to.be.an.instanceof(MarkdownCell);
        const prev = widget.widgets[0];
        expect(prev).to.be.an.instanceof(MarkdownCell);
      });

      it('should create two empty cells if there is no content', () => {
        widget.activeCell.model.value.text = '';
        NotebookActions.splitCell(widget);
        expect(widget.activeCell.model.value.text).to.equal('');
        const prev = widget.widgets[0];
        expect(prev.model.value.text).to.equal('');
      });

      it('should be a no-op if there is no model', () => {
        widget.model = null;
        NotebookActions.splitCell(widget);
        expect(widget.activeCell).to.be.undefined;
      });

      it('should preserve the widget mode', () => {
        NotebookActions.splitCell(widget);
        expect(widget.mode).to.equal('command');
        widget.mode = 'edit';
        NotebookActions.splitCell(widget);
        expect(widget.mode).to.equal('edit');
      });

      it('should be undo-able', () => {
        const source = widget.activeCell.model.value.text;
        const count = widget.widgets.length;
        NotebookActions.splitCell(widget);
        NotebookActions.undo(widget);
        expect(widget.widgets.length).to.equal(count);
        const cell = widget.widgets[0];
        expect(cell.model.value.text).to.equal(source);
      });
    });

    describe('#mergeCells', () => {
      it('should merge the selected cells', () => {
        let source = widget.activeCell.model.value.text + '\n\n';
        let next = widget.widgets[1];
        widget.select(next);
        source += next.model.value.text + '\n\n';
        next = widget.widgets[2];
        widget.select(next);
        source += next.model.value.text;
        const count = widget.widgets.length;
        NotebookActions.mergeCells(widget);
        expect(widget.widgets.length).to.equal(count - 2);
        expect(widget.activeCell.model.value.text).to.equal(source);
      });

      it('should be a no-op if there is no model', () => {
        widget.model = null;
        NotebookActions.mergeCells(widget);
        expect(widget.activeCell).to.be.undefined;
      });

      it('should select the next cell if there is only one cell selected', () => {
        let source = widget.activeCell.model.value.text + '\n\n';
        const next = widget.widgets[1];
        source += next.model.value.text;
        NotebookActions.mergeCells(widget);
        expect(widget.activeCell.model.value.text).to.equal(source);
      });

      it('should clear the outputs of a code cell', () => {
        NotebookActions.mergeCells(widget);
        const cell = widget.activeCell as CodeCell;
        expect(cell.model.outputs.length).to.equal(0);
      });

      it('should preserve the widget mode', () => {
        widget.mode = 'edit';
        NotebookActions.mergeCells(widget);
        expect(widget.mode).to.equal('edit');
        widget.mode = 'command';
        NotebookActions.mergeCells(widget);
        expect(widget.mode).to.equal('command');
      });

      it('should be undo-able', () => {
        const source = widget.activeCell.model.value.text;
        const count = widget.widgets.length;
        NotebookActions.mergeCells(widget);
        NotebookActions.undo(widget);
        expect(widget.widgets.length).to.equal(count);
        const cell = widget.widgets[0];
        expect(cell.model.value.text).to.equal(source);
      });

      it('should unrender a markdown cell', () => {
        NotebookActions.changeCellType(widget, 'markdown');
        let cell = widget.activeCell as MarkdownCell;
        cell.rendered = true;
        NotebookActions.mergeCells(widget);
        cell = widget.activeCell as MarkdownCell;
        expect(cell.rendered).to.equal(false);
        expect(widget.mode).to.equal('command');
      });

      it('should preserve the cell type of the active cell', () => {
        NotebookActions.changeCellType(widget, 'raw');
        NotebookActions.mergeCells(widget);
        expect(widget.activeCell).to.be.an.instanceof(RawCell);
        expect(widget.mode).to.equal('command');
      });
    });

    describe('#deleteCells()', () => {
      it('should delete the selected cells', () => {
        const next = widget.widgets[1];
        widget.select(next);
        const count = widget.widgets.length;
        NotebookActions.deleteCells(widget);
        expect(widget.widgets.length).to.equal(count - 2);
      });

      it('should increment deletedCells model when cells deleted', () => {
        let next = widget.widgets[1];
        widget.select(next);
        let count = widget.model.deletedCells.length;
        NotebookActions.deleteCells(widget);
        expect(widget.model.deletedCells.length).to.equal(count + 2);
      });

      it('should be a no-op if there is no model', () => {
        widget.model = null;
        NotebookActions.deleteCells(widget);
        expect(widget.activeCell).to.be.undefined;
      });

      it('should switch to command mode', () => {
        widget.mode = 'edit';
        NotebookActions.deleteCells(widget);
        expect(widget.mode).to.equal('command');
      });

      it('should activate the cell after the last selected cell', () => {
        widget.activeCellIndex = 4;
        const prev = widget.widgets[2];
        widget.select(prev);
        NotebookActions.deleteCells(widget);
        expect(widget.activeCellIndex).to.equal(3);
      });

      it('should select the previous cell if the last cell is deleted', () => {
        widget.select(widget.widgets[widget.widgets.length - 1]);
        NotebookActions.deleteCells(widget);
        expect(widget.activeCellIndex).to.equal(widget.widgets.length - 1);
      });

      it('should add a code cell if all cells are deleted', async () => {
        for (let i = 0; i < widget.widgets.length; i++) {
          widget.select(widget.widgets[i]);
        }
        NotebookActions.deleteCells(widget);
        await sleep();
        expect(widget.widgets.length).to.equal(1);
        expect(widget.activeCell).to.be.an.instanceof(CodeCell);
      });

      it('should be undo-able', () => {
        const next = widget.widgets[1];
        widget.select(next);
        const source = widget.activeCell.model.value.text;
        const count = widget.widgets.length;
        NotebookActions.deleteCells(widget);
        NotebookActions.undo(widget);
        expect(widget.widgets.length).to.equal(count);
        const cell = widget.widgets[0];
        expect(cell.model.value.text).to.equal(source);
      });

      it('should be undo-able if all the cells are deleted', () => {
        for (let i = 0; i < widget.widgets.length; i++) {
          widget.select(widget.widgets[i]);
        }
        const count = widget.widgets.length;
        const source = widget.widgets[1].model.value.text;
        NotebookActions.deleteCells(widget);
        NotebookActions.undo(widget);
        expect(widget.widgets.length).to.equal(count);
        expect(widget.widgets[1].model.value.text).to.equal(source);
      });
    });

    describe('#insertAbove()', () => {
      it('should insert a code cell above the active cell', () => {
        const count = widget.widgets.length;
        NotebookActions.insertAbove(widget);
        expect(widget.activeCellIndex).to.equal(0);
        expect(widget.widgets.length).to.equal(count + 1);
        expect(widget.activeCell).to.be.an.instanceof(CodeCell);
      });

      it('should be a no-op if there is no model', () => {
        widget.model = null;
        NotebookActions.insertAbove(widget);
        expect(widget.activeCell).to.be.undefined;
      });

      it('should widget mode should be preserved', () => {
        NotebookActions.insertAbove(widget);
        expect(widget.mode).to.equal('command');
        widget.mode = 'edit';
        NotebookActions.insertAbove(widget);
        expect(widget.mode).to.equal('edit');
      });

      it('should be undo-able', () => {
        const count = widget.widgets.length;
        NotebookActions.insertAbove(widget);
        NotebookActions.undo(widget);
        expect(widget.widgets.length).to.equal(count);
      });

      it('should clear the existing selection', () => {
        for (let i = 0; i < widget.widgets.length; i++) {
          widget.select(widget.widgets[i]);
        }
        NotebookActions.insertAbove(widget);
        for (let i = 0; i < widget.widgets.length; i++) {
          if (i === widget.activeCellIndex) {
            continue;
          }
          expect(widget.isSelected(widget.widgets[i])).to.equal(false);
        }
      });

      it('should be the new active cell', () => {
        NotebookActions.insertAbove(widget);
        expect(widget.activeCell.model.value.text).to.equal('');
      });
    });

    describe('#insertBelow()', () => {
      it('should insert a code cell below the active cell', () => {
        const count = widget.widgets.length;
        NotebookActions.insertBelow(widget);
        expect(widget.activeCellIndex).to.equal(1);
        expect(widget.widgets.length).to.equal(count + 1);
        expect(widget.activeCell).to.be.an.instanceof(CodeCell);
      });

      it('should be a no-op if there is no model', () => {
        widget.model = null;
        NotebookActions.insertBelow(widget);
        expect(widget.activeCell).to.be.undefined;
      });

      it('should widget mode should be preserved', () => {
        NotebookActions.insertBelow(widget);
        expect(widget.mode).to.equal('command');
        widget.mode = 'edit';
        NotebookActions.insertBelow(widget);
        expect(widget.mode).to.equal('edit');
      });

      it('should be undo-able', () => {
        const count = widget.widgets.length;
        NotebookActions.insertBelow(widget);
        NotebookActions.undo(widget);
        expect(widget.widgets.length).to.equal(count);
      });

      it('should clear the existing selection', () => {
        for (let i = 0; i < widget.widgets.length; i++) {
          widget.select(widget.widgets[i]);
        }
        NotebookActions.insertBelow(widget);
        for (let i = 0; i < widget.widgets.length; i++) {
          if (i === widget.activeCellIndex) {
            continue;
          }
          expect(widget.isSelected(widget.widgets[i])).to.equal(false);
        }
      });

      it('should be the new active cell', () => {
        NotebookActions.insertBelow(widget);
        expect(widget.activeCell.model.value.text).to.equal('');
      });
    });

    describe('#changeCellType()', () => {
      it('should change the selected cell type(s)', () => {
        let next = widget.widgets[1];
        widget.select(next);
        NotebookActions.changeCellType(widget, 'raw');
        expect(widget.activeCell).to.be.an.instanceof(RawCell);
        next = widget.widgets[widget.activeCellIndex + 1];
        expect(next).to.be.an.instanceof(RawCell);
      });

      it('should be a no-op if there is no model', () => {
        widget.model = null;
        NotebookActions.changeCellType(widget, 'code');
        expect(widget.activeCell).to.be.undefined;
      });

      it('should preserve the widget mode', () => {
        NotebookActions.changeCellType(widget, 'code');
        expect(widget.mode).to.equal('command');
        widget.mode = 'edit';
        NotebookActions.changeCellType(widget, 'raw');
        expect(widget.mode).to.equal('edit');
      });

      it('should be undo-able', () => {
        NotebookActions.changeCellType(widget, 'raw');
        NotebookActions.undo(widget);
        const cell = widget.widgets[0];
        expect(cell).to.be.an.instanceof(CodeCell);
      });

      it('should clear the existing selection', () => {
        for (let i = 0; i < widget.widgets.length; i++) {
          widget.select(widget.widgets[i]);
        }
        NotebookActions.changeCellType(widget, 'raw');
        for (let i = 0; i < widget.widgets.length; i++) {
          if (i === widget.activeCellIndex) {
            continue;
          }
          expect(widget.isSelected(widget.widgets[i])).to.equal(false);
        }
      });

      it('should unrender markdown cells', () => {
        NotebookActions.changeCellType(widget, 'markdown');
        const cell = widget.activeCell as MarkdownCell;
        expect(cell.rendered).to.equal(false);
      });
    });

    describe('#run()', () => {
      it('should run the selected cells', async () => {
        const next = widget.widgets[1] as MarkdownCell;
        widget.select(next);
        const cell = widget.activeCell as CodeCell;
        cell.model.outputs.clear();
        next.rendered = false;
        const result = await NotebookActions.run(widget, session);
        expect(result).to.equal(true);
        expect(cell.model.outputs.length).to.be.above(0);
        expect(next.rendered).to.equal(true);
      });

      it('should delete deletedCells metadata when cell run', () => {
        let cell = widget.activeCell as CodeCell;
        cell.model.outputs.clear();
        return NotebookActions.run(widget, session).then(result => {
          expect(result).to.equal(true);
          expect(widget.model.deletedCells.length).to.equal(0);
        });
      });

      it('should be a no-op if there is no model', async () => {
        widget.model = null;
        const result = await NotebookActions.run(widget, session);
        expect(result).to.equal(false);
      });

      it('should activate the last selected cell', async () => {
        const other = widget.widgets[2];
        widget.select(other);
        other.model.value.text = 'a = 1';
        const result = await NotebookActions.run(widget, session);
        expect(result).to.equal(true);
        expect(widget.activeCell).to.equal(other);
      });

      it('should clear the selection', async () => {
        const next = widget.widgets[1];
        widget.select(next);
        const result = await NotebookActions.run(widget, session);
        expect(result).to.equal(true);
        expect(widget.isSelected(widget.widgets[0])).to.equal(false);
      });

      it('should change to command mode', async () => {
        widget.mode = 'edit';
        const result = await NotebookActions.run(widget, session);
        expect(result).to.equal(true);
        expect(widget.mode).to.equal('command');
      });

      it('should handle no session', async () => {
        const result = await NotebookActions.run(widget, null);
        expect(result).to.equal(true);
        const cell = widget.activeCell as CodeCell;
        expect(cell.model.executionCount).to.be.null;
      });

      it('should stop executing code cells on an error', async () => {
        let cell = widget.model.contentFactory.createCodeCell({});
        cell.value.text = ERROR_INPUT;
        widget.model.cells.insert(2, cell);
        widget.select(widget.widgets[2]);
        cell = widget.model.contentFactory.createCodeCell({});
        widget.model.cells.push(cell);
        widget.select(widget.widgets[widget.widgets.length - 1]);
        const result = await NotebookActions.run(widget, ipySession);
        expect(result).to.equal(false);
        expect(cell.executionCount).to.be.null;
        await ipySession.kernel.restart();
      });

      it('should render all markdown cells on an error', async () => {
        const cell = widget.model.contentFactory.createMarkdownCell({});
        widget.model.cells.push(cell);
        const child = widget.widgets[widget.widgets.length - 1] as MarkdownCell;
        child.rendered = false;
        widget.select(child);
        widget.activeCell.model.value.text = ERROR_INPUT;
        const result = await NotebookActions.run(widget, ipySession);
        expect(result).to.equal(false);
        expect(child.rendered).to.equal(true);
        await ipySession.kernel.restart();
      });
    });

    describe('#runAndAdvance()', () => {
      it('should run the selected cells ', async () => {
        const next = widget.widgets[1] as MarkdownCell;
        widget.select(next);
        const cell = widget.activeCell as CodeCell;
        cell.model.outputs.clear();
        next.rendered = false;
        const result = await NotebookActions.runAndAdvance(widget, session);
        expect(result).to.equal(true);
        expect(cell.model.outputs.length).to.be.above(0);
        expect(next.rendered).to.equal(true);
      });

      it('should be a no-op if there is no model', async () => {
        widget.model = null;
        const result = await NotebookActions.runAndAdvance(widget, session);
        expect(result).to.equal(false);
      });

      it('should clear the existing selection', async () => {
        const next = widget.widgets[2];
        widget.select(next);
        const result = await NotebookActions.runAndAdvance(widget, ipySession);
        expect(result).to.equal(false);
        expect(widget.isSelected(widget.widgets[0])).to.equal(false);
        await ipySession.kernel.restart();
      });

      it('should change to command mode', async () => {
        widget.mode = 'edit';
        const result = await NotebookActions.runAndAdvance(widget, session);
        expect(result).to.equal(true);
        expect(widget.mode).to.equal('command');
      });

      it('should activate the cell after the last selected cell', async () => {
        const next = widget.widgets[3] as MarkdownCell;
        widget.select(next);
        const result = await NotebookActions.runAndAdvance(widget, session);
        expect(result).to.equal(true);
        expect(widget.activeCellIndex).to.equal(4);
      });

      it('should create a new code cell in edit mode if necessary', async () => {
        const count = widget.widgets.length;
        widget.activeCellIndex = count - 1;
        const result = await NotebookActions.runAndAdvance(widget, session);
        expect(result).to.equal(true);
        expect(widget.widgets.length).to.equal(count + 1);
        expect(widget.activeCell).to.be.an.instanceof(CodeCell);
        expect(widget.mode).to.equal('edit');
      });

      it('should allow an undo of the new cell', async () => {
        const count = widget.widgets.length;
        widget.activeCellIndex = count - 1;
        const result = await NotebookActions.runAndAdvance(widget, session);
        expect(result).to.equal(true);
        NotebookActions.undo(widget);
        expect(widget.widgets.length).to.equal(count);
      });

      it('should stop executing code cells on an error', async () => {
        widget.activeCell.model.value.text = ERROR_INPUT;
        const cell = widget.model.contentFactory.createCodeCell({});
        widget.model.cells.push(cell);
        widget.select(widget.widgets[widget.widgets.length - 1]);
        const result = await NotebookActions.runAndAdvance(widget, ipySession);
        expect(result).to.equal(false);
        expect(cell.executionCount).to.be.null;
        await ipySession.kernel.restart();
      });

      it('should render all markdown cells on an error', async () => {
        widget.activeCell.model.value.text = ERROR_INPUT;
        const cell = widget.widgets[1] as MarkdownCell;
        cell.rendered = false;
        widget.select(cell);
        const result = await NotebookActions.runAndAdvance(widget, ipySession);
        expect(result).to.equal(false);
        expect(cell.rendered).to.equal(true);
        expect(widget.activeCellIndex).to.equal(2);
        await ipySession.kernel.restart();
      });
    });

    describe('#runAndInsert()', () => {
      it('should run the selected cells ', async () => {
        const next = widget.widgets[1] as MarkdownCell;
        widget.select(next);
        const cell = widget.activeCell as CodeCell;
        cell.model.outputs.clear();
        next.rendered = false;
        const result = await NotebookActions.runAndInsert(widget, session);
        expect(result).to.equal(true);
        expect(cell.model.outputs.length).to.be.above(0);
        expect(next.rendered).to.equal(true);
      });

      it('should be a no-op if there is no model', async () => {
        widget.model = null;
        const result = await NotebookActions.runAndInsert(widget, session);
        expect(result).to.equal(false);
      });

      it('should clear the existing selection', async () => {
        const next = widget.widgets[1];
        widget.select(next);
        const result = await NotebookActions.runAndInsert(widget, session);
        expect(result).to.equal(true);
        expect(widget.isSelected(widget.widgets[0])).to.equal(false);
      });

      it('should insert a new code cell in edit mode after the last selected cell', async () => {
        const next = widget.widgets[2];
        widget.select(next);
        next.model.value.text = 'a = 1';
        const count = widget.widgets.length;
        const result = await NotebookActions.runAndInsert(widget, session);
        expect(result).to.equal(true);
        expect(widget.activeCell).to.be.an.instanceof(CodeCell);
        expect(widget.mode).to.equal('edit');
        expect(widget.widgets.length).to.equal(count + 1);
      });

      it('should allow an undo of the cell insert', async () => {
        const next = widget.widgets[2];
        widget.select(next);
        next.model.value.text = 'a = 1';
        const count = widget.widgets.length;
        const result = await NotebookActions.runAndInsert(widget, session);
        expect(result).to.equal(true);
        NotebookActions.undo(widget);
        expect(widget.widgets.length).to.equal(count);
      });

      it('should stop executing code cells on an error', async () => {
        widget.activeCell.model.value.text = ERROR_INPUT;
        const cell = widget.model.contentFactory.createCodeCell({});
        widget.model.cells.push(cell);
        widget.select(widget.widgets[widget.widgets.length - 1]);
        const result = await NotebookActions.runAndInsert(widget, ipySession);
        expect(result).to.equal(false);
        expect(cell.executionCount).to.be.null;
        await ipySession.kernel.restart();
      });

      it('should render all markdown cells on an error', async () => {
        widget.activeCell.model.value.text = ERROR_INPUT;
        const cell = widget.widgets[1] as MarkdownCell;
        cell.rendered = false;
        widget.select(cell);
        const result = await NotebookActions.runAndInsert(widget, ipySession);
        expect(result).to.equal(false);
        expect(cell.rendered).to.equal(true);
        expect(widget.activeCellIndex).to.equal(2);
        await ipySession.kernel.restart();
      });
    });

    describe('#runAll()', () => {
      beforeEach(() => {
        // Make sure all cells have valid code.
        widget.widgets[2].model.value.text = 'a = 1';
      });

      it('should run all of the cells in the notebok', async () => {
        const next = widget.widgets[1] as MarkdownCell;
        const cell = widget.activeCell as CodeCell;
        cell.model.outputs.clear();
        next.rendered = false;
        const result = await NotebookActions.runAll(widget, session);
        expect(result).to.equal(true);
        expect(cell.model.outputs.length).to.be.above(0);
        expect(next.rendered).to.equal(true);
      });

      it('should be a no-op if there is no model', async () => {
        widget.model = null;
        const result = await NotebookActions.runAll(widget, session);
        expect(result).to.equal(false);
      });

      it('should change to command mode', async () => {
        widget.mode = 'edit';
        const result = await NotebookActions.runAll(widget, session);
        expect(result).to.equal(true);
        expect(widget.mode).to.equal('command');
      });

      it('should clear the existing selection', async () => {
        const next = widget.widgets[2];
        widget.select(next);
        const result = await NotebookActions.runAll(widget, session);
        expect(result).to.equal(true);
        expect(widget.isSelected(widget.widgets[2])).to.equal(false);
      });

      it('should activate the last cell', async () => {
        await NotebookActions.runAll(widget, session);
        expect(widget.activeCellIndex).to.equal(widget.widgets.length - 1);
      });

      it('should stop executing code cells on an error', async () => {
        widget.activeCell.model.value.text = ERROR_INPUT;
        const cell = widget.model.contentFactory.createCodeCell({});
        widget.model.cells.push(cell);
        const result = await NotebookActions.runAll(widget, ipySession);
        expect(result).to.equal(false);
        expect(cell.executionCount).to.be.null;
        expect(widget.activeCellIndex).to.equal(widget.widgets.length - 1);
        await ipySession.kernel.restart();
      });

      it('should render all markdown cells on an error', async () => {
        widget.activeCell.model.value.text = ERROR_INPUT;
        const cell = widget.widgets[1] as MarkdownCell;
        cell.rendered = false;
        const result = await NotebookActions.runAll(widget, ipySession);
        expect(result).to.equal(false);
        expect(cell.rendered).to.equal(true);
        await ipySession.kernel.restart();
      });
    });

    describe('#selectAbove(`)', () => {
      it('should select the cell above the active cell', () => {
        widget.activeCellIndex = 1;
        NotebookActions.selectAbove(widget);
        expect(widget.activeCellIndex).to.equal(0);
      });

      it('should be a no-op if there is no model', () => {
        widget.model = null;
        NotebookActions.selectAbove(widget);
        expect(widget.activeCellIndex).to.equal(-1);
      });

      it('should not wrap around to the bottom', () => {
        NotebookActions.selectAbove(widget);
        expect(widget.activeCellIndex).to.equal(0);
      });

      it('should preserve the mode', () => {
        widget.activeCellIndex = 2;
        NotebookActions.selectAbove(widget);
        expect(widget.mode).to.equal('command');
        widget.mode = 'edit';
        NotebookActions.selectAbove(widget);
        expect(widget.mode).to.equal('edit');
      });
    });

    describe('#selectBelow()', () => {
      it('should select the cell below the active cell', () => {
        NotebookActions.selectBelow(widget);
        expect(widget.activeCellIndex).to.equal(1);
      });

      it('should be a no-op if there is no model', () => {
        widget.model = null;
        NotebookActions.selectBelow(widget);
        expect(widget.activeCellIndex).to.equal(-1);
      });

      it('should not wrap around to the top', () => {
        widget.activeCellIndex = widget.widgets.length - 1;
        NotebookActions.selectBelow(widget);
        expect(widget.activeCellIndex).to.not.equal(0);
      });

      it('should preserve the mode', () => {
        widget.activeCellIndex = 2;
        NotebookActions.selectBelow(widget);
        expect(widget.mode).to.equal('command');
        widget.mode = 'edit';
        NotebookActions.selectBelow(widget);
        expect(widget.mode).to.equal('edit');
      });
    });

    describe('#extendSelectionAbove()', () => {
      it('should extend the selection to the cell above', () => {
        widget.activeCellIndex = 1;
        NotebookActions.extendSelectionAbove(widget);
        expect(widget.isSelected(widget.widgets[0])).to.equal(true);
      });

      it('should be a no-op if there is no model', () => {
        widget.model = null;
        NotebookActions.extendSelectionAbove(widget);
        expect(widget.activeCellIndex).to.equal(-1);
      });

      it('should change to command mode if there is a selection', () => {
        widget.mode = 'edit';
        widget.activeCellIndex = 1;
        NotebookActions.extendSelectionAbove(widget);
        expect(widget.mode).to.equal('command');
      });

      it('should not wrap around to the bottom', () => {
        widget.mode = 'edit';
        NotebookActions.extendSelectionAbove(widget);
        expect(widget.activeCellIndex).to.equal(0);
        const last = widget.widgets[widget.widgets.length - 1];
        expect(widget.isSelected(last)).to.equal(false);
        expect(widget.mode).to.equal('edit');
      });

      it('should deselect the current cell if the cell above is selected', () => {
        NotebookActions.extendSelectionBelow(widget);
        NotebookActions.extendSelectionBelow(widget);
        const cell = widget.activeCell;
        NotebookActions.extendSelectionAbove(widget);
        expect(widget.isSelected(cell)).to.equal(false);
      });

      it('should select only the first cell if we move from the second to first', () => {
        NotebookActions.extendSelectionBelow(widget);
        const cell = widget.activeCell;
        NotebookActions.extendSelectionAbove(widget);
        expect(widget.isSelected(cell)).to.equal(false);
        expect(widget.activeCellIndex).to.equal(0);
      });

      it('should activate the cell', () => {
        widget.activeCellIndex = 1;
        NotebookActions.extendSelectionAbove(widget);
        expect(widget.activeCellIndex).to.equal(0);
      });
    });

    describe('#extendSelectionBelow()', () => {
      it('should extend the selection to the cell below', () => {
        NotebookActions.extendSelectionBelow(widget);
        expect(widget.isSelected(widget.widgets[0])).to.equal(true);
        expect(widget.isSelected(widget.widgets[1])).to.equal(true);
      });

      it('should be a no-op if there is no model', () => {
        widget.model = null;
        NotebookActions.extendSelectionBelow(widget);
        expect(widget.activeCellIndex).to.equal(-1);
      });

      it('should change to command mode if there is a selection', () => {
        widget.mode = 'edit';
        NotebookActions.extendSelectionBelow(widget);
        expect(widget.mode).to.equal('command');
      });

      it('should not wrap around to the top', () => {
        const last = widget.widgets.length - 1;
        widget.activeCellIndex = last;
        widget.mode = 'edit';
        NotebookActions.extendSelectionBelow(widget);
        expect(widget.activeCellIndex).to.equal(last);
        expect(widget.isSelected(widget.widgets[0])).to.equal(false);
        expect(widget.mode).to.equal('edit');
      });

      it('should deselect the current cell if the cell below is selected', () => {
        const last = widget.widgets.length - 1;
        widget.activeCellIndex = last;
        NotebookActions.extendSelectionAbove(widget);
        NotebookActions.extendSelectionAbove(widget);
        const current = widget.activeCell;
        NotebookActions.extendSelectionBelow(widget);
        expect(widget.isSelected(current)).to.equal(false);
      });

      it('should select only the last cell if we move from the second last to last', () => {
        const last = widget.widgets.length - 1;
        widget.activeCellIndex = last;
        NotebookActions.extendSelectionAbove(widget);
        const current = widget.activeCell;
        NotebookActions.extendSelectionBelow(widget);
        expect(widget.isSelected(current)).to.equal(false);
        expect(widget.activeCellIndex).to.equal(last);
      });

      it('should activate the cell', () => {
        NotebookActions.extendSelectionBelow(widget);
        expect(widget.activeCellIndex).to.equal(1);
      });
    });

    describe('#moveUp()', () => {
      it('should move the selected cells up', () => {
        widget.activeCellIndex = 2;
        NotebookActions.extendSelectionAbove(widget);
        NotebookActions.moveUp(widget);
        expect(widget.isSelected(widget.widgets[0])).to.equal(true);
        expect(widget.isSelected(widget.widgets[1])).to.equal(true);
        expect(widget.isSelected(widget.widgets[2])).to.equal(false);
        expect(widget.activeCellIndex).to.equal(0);
      });

      it('should be a no-op if there is no model', () => {
        widget.model = null;
        NotebookActions.moveUp(widget);
        expect(widget.activeCellIndex).to.equal(-1);
      });

      it('should not wrap around to the bottom', () => {
        expect(widget.activeCellIndex).to.equal(0);
        NotebookActions.moveUp(widget);
        expect(widget.activeCellIndex).to.equal(0);
      });

      it('should be undo-able', () => {
        widget.activeCellIndex++;
        const source = widget.activeCell.model.value.text;
        NotebookActions.moveUp(widget);
        expect(widget.model.cells.get(0).value.text).to.equal(source);
        NotebookActions.undo(widget);
        expect(widget.model.cells.get(1).value.text).to.equal(source);
      });
    });

    describe('#moveDown()', () => {
      it('should move the selected cells down', () => {
        NotebookActions.extendSelectionBelow(widget);
        NotebookActions.moveDown(widget);
        expect(widget.isSelected(widget.widgets[0])).to.equal(false);
        expect(widget.isSelected(widget.widgets[1])).to.equal(true);
        expect(widget.isSelected(widget.widgets[2])).to.equal(true);
        expect(widget.activeCellIndex).to.equal(2);
      });

      it('should be a no-op if there is no model', () => {
        widget.model = null;
        NotebookActions.moveUp(widget);
        expect(widget.activeCellIndex).to.equal(-1);
      });

      it('should not wrap around to the top', () => {
        widget.activeCellIndex = widget.widgets.length - 1;
        NotebookActions.moveDown(widget);
        expect(widget.activeCellIndex).to.equal(widget.widgets.length - 1);
      });

      it('should be undo-able', () => {
        const source = widget.activeCell.model.value.text;
        NotebookActions.moveDown(widget);
        expect(widget.model.cells.get(1).value.text).to.equal(source);
        NotebookActions.undo(widget);
        expect(widget.model.cells.get(0).value.text).to.equal(source);
      });
    });

    describe('#copy()', () => {
      it('should copy the selected cells to a NBTestUtils.clipboard', () => {
        const next = widget.widgets[1];
        widget.select(next);
        NotebookActions.copy(widget);
        expect(NBTestUtils.clipboard.hasData(JUPYTER_CELL_MIME)).to.equal(true);
        const data = NBTestUtils.clipboard.getData(JUPYTER_CELL_MIME);
        expect(data.length).to.equal(2);
      });

      it('should be a no-op if there is no model', () => {
        widget.model = null;
        NotebookActions.copy(widget);
        expect(NBTestUtils.clipboard.hasData(JUPYTER_CELL_MIME)).to.equal(
          false
        );
      });

      it('should change to command mode', () => {
        widget.mode = 'edit';
        NotebookActions.copy(widget);
        expect(widget.mode).to.equal('command');
      });
    });

    describe('#cut()', () => {
      it('should cut the selected cells to a NBTestUtils.clipboard', () => {
        const next = widget.widgets[1];
        widget.select(next);
        const count = widget.widgets.length;
        NotebookActions.cut(widget);
        expect(widget.widgets.length).to.equal(count - 2);
      });

      it('should be a no-op if there is no model', () => {
        widget.model = null;
        NotebookActions.cut(widget);
        expect(NBTestUtils.clipboard.hasData(JUPYTER_CELL_MIME)).to.equal(
          false
        );
      });

      it('should change to command mode', () => {
        widget.mode = 'edit';
        NotebookActions.cut(widget);
        expect(widget.mode).to.equal('command');
      });

      it('should be undo-able', () => {
        const source = widget.activeCell.model.value.text;
        NotebookActions.cut(widget);
        NotebookActions.undo(widget);
        expect(widget.widgets[0].model.value.text).to.equal(source);
      });

      it('should add a new code cell if all cells were cut', async () => {
        for (let i = 0; i < widget.widgets.length; i++) {
          widget.select(widget.widgets[i]);
        }
        NotebookActions.cut(widget);
        await sleep();
        expect(widget.widgets.length).to.equal(1);
        expect(widget.activeCell).to.be.an.instanceof(CodeCell);
      });
    });

    describe('#paste()', () => {
      it('should paste cells from a NBTestUtils.clipboard', () => {
        const source = widget.activeCell.model.value.text;
        const next = widget.widgets[1];
        widget.select(next);
        const count = widget.widgets.length;
        NotebookActions.cut(widget);
        widget.activeCellIndex = 1;
        NotebookActions.paste(widget);
        expect(widget.widgets.length).to.equal(count);
        expect(widget.widgets[2].model.value.text).to.equal(source);
        expect(widget.activeCellIndex).to.equal(3);
      });

      it('should be a no-op if there is no model', () => {
        NotebookActions.copy(widget);
        widget.model = null;
        NotebookActions.paste(widget);
        expect(widget.activeCellIndex).to.equal(-1);
      });

      it('should be a no-op if there is no cell data on the NBTestUtils.clipboard', () => {
        const count = widget.widgets.length;
        NotebookActions.paste(widget);
        expect(widget.widgets.length).to.equal(count);
      });

      it('should change to command mode', () => {
        widget.mode = 'edit';
        NotebookActions.cut(widget);
        NotebookActions.paste(widget);
        expect(widget.mode).to.equal('command');
      });

      it('should be undo-able', () => {
        const next = widget.widgets[1];
        widget.select(next);
        const count = widget.widgets.length;
        NotebookActions.cut(widget);
        widget.activeCellIndex = 1;
        NotebookActions.paste(widget);
        NotebookActions.undo(widget);
        expect(widget.widgets.length).to.equal(count - 2);
      });
    });

    describe('#undo()', () => {
      it('should undo a cell action', () => {
        const count = widget.widgets.length;
        const next = widget.widgets[1];
        widget.select(next);
        NotebookActions.deleteCells(widget);
        NotebookActions.undo(widget);
        expect(widget.widgets.length).to.equal(count);
      });

      it('should switch the widget to command mode', () => {
        widget.mode = 'edit';
        NotebookActions.undo(widget);
        expect(widget.mode).to.equal('command');
      });

      it('should be a no-op if there is no model', () => {
        widget.model = null;
        NotebookActions.undo(widget);
        expect(widget.activeCellIndex).to.equal(-1);
      });

      it('should be a no-op if there are no cell actions to undo', () => {
        const count = widget.widgets.length;
        NotebookActions.deleteCells(widget);
        widget.model.cells.clearUndo();
        NotebookActions.undo(widget);
        expect(widget.widgets.length).to.equal(count - 1);
      });
    });

    describe('#redo()', () => {
      it('should redo a cell action', () => {
        const count = widget.widgets.length;
        const next = widget.widgets[1];
        widget.select(next);
        NotebookActions.deleteCells(widget);
        NotebookActions.undo(widget);
        NotebookActions.redo(widget);
        expect(widget.widgets.length).to.equal(count - 2);
      });

      it('should switch the widget to command mode', () => {
        NotebookActions.undo(widget);
        widget.mode = 'edit';
        NotebookActions.redo(widget);
        expect(widget.mode).to.equal('command');
      });

      it('should be a no-op if there is no model', () => {
        NotebookActions.undo(widget);
        widget.model = null;
        NotebookActions.redo(widget);
        expect(widget.activeCellIndex).to.equal(-1);
      });

      it('should be a no-op if there are no cell actions to redo', () => {
        const count = widget.widgets.length;
        NotebookActions.redo(widget);
        expect(widget.widgets.length).to.equal(count);
      });
    });

    describe('#toggleAllLineNumbers()', () => {
      it('should toggle line numbers on all cells', () => {
        const state = widget.activeCell.editor.getOption('lineNumbers');
        NotebookActions.toggleAllLineNumbers(widget);
        for (let i = 0; i < widget.widgets.length; i++) {
          const lineNumbers = widget.widgets[i].editor.getOption('lineNumbers');
          expect(lineNumbers).to.equal(!state);
        }
      });

      it('should be based on the state of the active cell', () => {
        const state = widget.activeCell.editor.getOption('lineNumbers');
        for (let i = 1; i < widget.widgets.length; i++) {
          widget.widgets[i].editor.setOption('lineNumbers', !state);
        }
        NotebookActions.toggleAllLineNumbers(widget);
        for (let i = 0; i < widget.widgets.length; i++) {
          const lineNumbers = widget.widgets[i].editor.getOption('lineNumbers');
          expect(lineNumbers).to.equal(!state);
        }
      });

      it('should preserve the widget mode', () => {
        NotebookActions.toggleAllLineNumbers(widget);
        expect(widget.mode).to.equal('command');
        widget.mode = 'edit';
        NotebookActions.toggleAllLineNumbers(widget);
        expect(widget.mode).to.equal('edit');
      });

      it('should be a no-op if there is no model', () => {
        widget.model = null;
        NotebookActions.toggleAllLineNumbers(widget);
        expect(widget.activeCellIndex).to.equal(-1);
      });
    });

    describe('#clearOutputs()', () => {
      it('should clear the outputs on the selected cells', () => {
        // Select the next code cell that has outputs.
        let index = 0;
        for (let i = 1; i < widget.widgets.length; i++) {
          const cell = widget.widgets[i];
          if (cell instanceof CodeCell && cell.model.outputs.length) {
            widget.select(cell);
            index = i;
            break;
          }
        }
        NotebookActions.clearOutputs(widget);
        let cell = widget.widgets[0] as CodeCell;
        expect(cell.model.outputs.length).to.equal(0);
        cell = widget.widgets[index] as CodeCell;
        expect(cell.model.outputs.length).to.equal(0);
      });

      it('should preserve the widget mode', () => {
        NotebookActions.clearOutputs(widget);
        expect(widget.mode).to.equal('command');
        widget.mode = 'edit';
        NotebookActions.clearOutputs(widget);
        expect(widget.mode).to.equal('edit');
      });

      it('should be a no-op if there is no model', () => {
        widget.model = null;
        NotebookActions.clearOutputs(widget);
        expect(widget.activeCellIndex).to.equal(-1);
      });
    });

    describe('#clearAllOutputs()', () => {
      it('should clear the outputs on all cells', () => {
        const next = widget.widgets[1];
        widget.select(next);
        NotebookActions.clearAllOutputs(widget);
        for (let i = 0; i < widget.widgets.length; i++) {
          const cell = widget.widgets[i];
          if (cell instanceof CodeCell) {
            expect(cell.model.outputs.length).to.equal(0);
          }
        }
      });

      it('should preserve the widget mode', () => {
        NotebookActions.clearAllOutputs(widget);
        expect(widget.mode).to.equal('command');
        widget.mode = 'edit';
        NotebookActions.clearAllOutputs(widget);
        expect(widget.mode).to.equal('edit');
      });

      it('should be a no-op if there is no model', () => {
        widget.model = null;
        NotebookActions.clearAllOutputs(widget);
        expect(widget.activeCellIndex).to.equal(-1);
      });
    });

    describe('#persistViewState()', () => {
      it('input hidden, output hidden and scrolled', () => {
        for (const cell of widget.widgets) {
          cell.inputHidden = true;
          if (cell instanceof CodeCell) {
            cell.outputHidden = true;
            cell.outputsScrolled = true;
          }
        }
        NotebookActions.persistViewState(widget);
        for (const cell of widget.widgets) {
          if (cell instanceof CodeCell) {
            expect(cell.model.metadata.get('collapsed')).to.equal(true);
            expect(cell.model.metadata.get('scrolled')).to.equal(true);
            expect(cell.model.metadata.get('jupyter')).to.deep.equal({
              source_hidden: true,
              outputs_hidden: true
            });
          } else {
            expect(cell.model.metadata.get('jupyter')).to.deep.equal({
              source_hidden: true
            });
          }
        }
      });

      it('input hidden, output hidden and not scrolled', () => {
        for (const cell of widget.widgets) {
          cell.inputHidden = false;
          if (cell instanceof CodeCell) {
            cell.outputHidden = false;
            cell.outputsScrolled = false;
          }
        }
        NotebookActions.persistViewState(widget);
        for (const cell of widget.widgets) {
          if (cell instanceof CodeCell) {
            expect(cell.model.metadata.has('collapsed')).to.equal(false);
            expect(cell.model.metadata.has('scrolled')).to.equal(false);
          }
          expect(cell.model.metadata.has('jupyter')).to.equal(false);
        }
      });

      it('input hidden, output shown and not scrolled', () => {
        for (const cell of widget.widgets) {
          cell.inputHidden = true;
          if (cell instanceof CodeCell) {
            cell.outputHidden = false;
            cell.outputsScrolled = false;
          }
        }
        NotebookActions.persistViewState(widget);
        for (const cell of widget.widgets) {
          if (cell instanceof CodeCell) {
            expect(cell.model.metadata.has('collapsed')).to.equal(false);
            expect(cell.model.metadata.has('scrolled')).to.equal(false);
          }
          expect(cell.model.metadata.get('jupyter')).to.deep.equal({
            source_hidden: true
          });
        }
      });
    });

    describe('#setMarkdownHeader()', () => {
      it('should set the markdown header level of selected cells', () => {
        const next = widget.widgets[1];
        widget.select(next);
        NotebookActions.setMarkdownHeader(widget, 2);
        expect(widget.activeCell.model.value.text.slice(0, 3)).to.equal('## ');
        expect(next.model.value.text.slice(0, 3)).to.equal('## ');
      });

      it('should convert the cells to markdown type', () => {
        NotebookActions.setMarkdownHeader(widget, 2);
        expect(widget.activeCell).to.be.an.instanceof(MarkdownCell);
      });

      it('should be clamped between 1 and 6', () => {
        NotebookActions.setMarkdownHeader(widget, -1);
        expect(widget.activeCell.model.value.text.slice(0, 2)).to.equal('# ');
        NotebookActions.setMarkdownHeader(widget, 10);
        expect(widget.activeCell.model.value.text.slice(0, 7)).to.equal(
          '###### '
        );
      });

      it('should be a no-op if there is no model', () => {
        widget.model = null;
        NotebookActions.setMarkdownHeader(widget, 1);
        expect(widget.activeCellIndex).to.equal(-1);
      });

      it('should replace an existing header', () => {
        widget.activeCell.model.value.text = '# foo';
        NotebookActions.setMarkdownHeader(widget, 2);
        expect(widget.activeCell.model.value.text).to.equal('## foo');
      });

      it('should replace leading white space', () => {
        widget.activeCell.model.value.text = '      foo';
        NotebookActions.setMarkdownHeader(widget, 2);
        expect(widget.activeCell.model.value.text).to.equal('## foo');
      });

      it('should unrender the cells', () => {
        NotebookActions.setMarkdownHeader(widget, 1);
        expect((widget.activeCell as MarkdownCell).rendered).to.equal(false);
      });
    });

    describe('#trust()', () => {
      it('should trust the notebook cells if the user accepts', async () => {
        const model = widget.model;
        widget.model.fromJSON(NBTestUtils.DEFAULT_CONTENT);
        const cell = model.cells.get(0);
        expect(cell.trusted).to.not.equal(true);
        let promise = NotebookActions.trust(widget);
        await acceptDialog();
        await promise;
        expect(cell.trusted).to.equal(true);
      });

      it('should not trust the notebook cells if the user aborts', async () => {
        const model = widget.model;
        model.fromJSON(NBTestUtils.DEFAULT_CONTENT);
        const cell = model.cells.get(0);
        expect(cell.trusted).to.not.equal(true);
        let promise = NotebookActions.trust(widget);
        await dismissDialog();
        await promise;
        expect(cell.trusted).to.not.equal(true);
      });

      it('should be a no-op if the model is `null`', async () => {
        widget.model = null;
        await NotebookActions.trust(widget);
      });

      it('should show a dialog if all cells are trusted', async () => {
        const model = widget.model;
        widget.model.fromJSON(NBTestUtils.DEFAULT_CONTENT);
        model.fromJSON(NBTestUtils.DEFAULT_CONTENT);
        for (let i = 0; i < model.cells.length; i++) {
          const cell = model.cells.get(i);
          cell.trusted = true;
        }
        const promise = NotebookActions.trust(widget);
        await acceptDialog();
        await promise;
      });
    });
  });
});